1. Field of the Invention
The present invention relates to an adhesive sheet for production of an electrostatic chucking device having an adsorptive surface composed of ceramic and to an electrostatic chucking device produced using the adhesive sheet.
2. Description of Related Art
In the industry of producing IC tips, a semiconductor wafer is fixed to an etching equipment using a chucking device, which is then subjected to an etching treatment in a vacuum to produce IC tips. As for the mechanism of the chucking device, there are mechanical type, vacuum type and electrostatic type. Among them, the electrostatic chucking device is used widely because of having advantages that it can be used in vacuum, it sufficiently holds the wafer even if some curvatures are in the wafer, and it can easily handled.
For example, Japanese Patent Application Laid-open No. 347352/1993 discloses an electrostatic chucking device of the following structure. Namely, an insulating film is laminated on a metal base, and an insulation maintenance board made of ceramic is laminated on the upper surface of the insulating film. An electric conduction film for electrostatic adsorption consisting of copper foil is formed on the under surface of the insulation maintenance board, and a wafer is laid on the upper surface of the insulation maintenance board. The insulating film is composed of polyimide adhesive layers laminated each on both sides of an insulating polyimide film substrate. Use of this insulating film secures electric insulation between the electric conduction film for electrostatic adsorption and the metal base. Adsorptity can be raised by making thin the insulation maintenance board made of ceramic. However, when the insulation maintenance board was made thin in this electrostatic chucking device, curvature of the adsorptive surface came to actualize by application of heat to the electrostatic chucking device. As the result, there became problems that not only the adsorptity for the wafer reduced but also the wafer became unable to cool enough.
Moreover, since the plasma processing temperature at the time of wafer processing becomes high in connection with the recent development of large-sized semiconductor wafers and the improvement in production efficiency, it becomes the subject of pressing need to solve the problem of the curvature of the insulation maintenance board made of ceramic, and, in addition, high heat resistance has come to be required for the electrostatic chucking device.
In order to improve the curvature of the adsorptive surface, the present inventors have proposed to provide an electric insulation elastic layer containing a rubber component and a phenolic antioxidant for the electrostatic chucking device (Japanese Patent Application Laid-open No. 215994/1999). The heat resistance of this electric insulation elastic layer however does not withstand the plasma processing temperature, which became higher. It was thus required for a heat-resistant improvement.
The present invention has been made in view of the above-mentioned circumstances, and the purpose of it is to solve the above-mentioned problems in the prior electrostatic chucking devices having an adsorptive surface made of ceramic. That is, an object of the present invention is to provide an adhesive sheet for electrostatic chucking device which has particularly high heat resistance. Another object is to provide an electrostatic chucking device using said adhesive sheet, which does not cause the curvature of the adsorptive surface.
The adhesive sheet according to the present invention for electrostatic chucking device, which is used for producing the electrostatic chucking device having an adsorptive surface made of ceramics, is characterized by comprising a silicone resin elastic layer and two thermosetting adhesive layers containing an epoxy resin or a phenol resin, each of which is laminated on both sides of said silicone resin elastic layer.
The electrostatic chucking device according to the present invention has an adsorptive surface made of ceramic, which is characterized by that an electrode layer and a ceramic layer having an adsorptive surface are laminated in this order on a metal base via the above-mentioned adhesive sheet, wherein two thermosetting adhesive layers containing an epoxy resin or a phenol resin, each of which is laminated on both sides of said silicone resin elastic layer.
In the adhesive sheet for electrostatic chucking device according to the present invention, it is preferable that the above-mentioned silicone resin elastic layer contains a filler and that a dynamic modulus in 0-125xc2x0 C. of said silicone resin elastic layer is in a range of 0.1 MPa-30 MPa.
Moreover, as for the above-mentioned thermosetting adhesive layer, it is preferable to contain at least one selected from the group consisting of polyamide resin, acrylonitrile-butadiene copolymer, polyester resin and polyimide resin, as an elastic component.
It is particularly preferable that the polyimide resin is composed of a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2). 
wherein W is a direct bond, an alkylene group having 1-4 carbon atoms, xe2x80x94Oxe2x80x94, xe2x80x94SO2xe2x80x94 or xe2x80x94COxe2x80x94, Ar is a divalent aromatic group having 1-4 aromatic rings, R1 and R6 are each an alkylene group having 1-4 carbon atoms or a group represented by the following formula (3): 
wherein Alk is an alkylene group having 1-4 carbon atoms which bonds to the silicone atom,
R2-R5 are each an alkyl group having 1-4 carbon atoms, and
n is an integer of 0-32.